Can you just host a git server yourself? Not trying to be snarky but seems doable.

You can. It's very doable. Plenty of people do it.

But the real value of GH was "social coding" - open public access to open public projects.

That's going to fragment, even if GL takes over. And that will be a loss.

The real problem is the lack of open public server infrastructure. In the same way that everyone has access to a browser, everyone should have access to a private server, which is secure-by-default, controllably networked, super easy to set up with a selection of server apps that include social, commerce, payments, and public/private sharing of various kinds, and cheap to run.

The centralised consumer internet - where servers are far beyond the skill level of most users and can be a nightmare to set up and administer, even for professionals - is one of the reasons we have giant predators like MS and Facebook.

What you call "social coding" is simply the convenience of contributing to a huge number of projects without needing a separate account or quasi-account (joining a mailing list, using OAuth/OpenID, etc.) for each. It is not necessary, it predates and doesn't need GitHub (as Sourceforge demonstrated 20 years ago), and it will simply move to other project hosting communities, with a modest decrease of convenience in the transition between one account and a few accounts.

I have a self-hosted git instance on a VPS. It's trivial to set up for doing personal projects, but it would take quite a bit more work to properly set it up so other people could clone repos or contribute. Depending on what GitHub features Zamicol is using, it could be a pretty large project to self-host.